
 /* <!-- 第三题大题 --> */
 // 选择<p>JavaScript</p>:
 var js = document.getElementById('test-p');
 // 选择<p>Python</p>,<p>Ruby</p>,<p>Swift</p>:
 var arr =  document.getElementsByClassName('c-red')[1].getElementsByTagName('p');
 // 选择<p>Haskell</p>:
 var haskell = document.getElementsByClassName('c-green')[1].lastElementChild;
 // 测试:
 if (!js || js.innerText !== 'JavaScript') {
     alert('选择JavaScript失败!');
 } else if (!arr || arr.length !== 3 || !arr[0] || !arr[1] || !arr[2] || arr[0].innerText !== 'Python' || arr[1].innerText !== 'Ruby' || arr[2].innerText !== 'Swift') {
     console.log('选择Python,Ruby,Swift失败!');
 } else if (!haskell || haskell.innerText !== 'Haskell') {
     console.log('选择Haskell失败!');
 } else {
     console.log('测试通过!');
 }
